A power supply circuit for electrical equipment generally comprises a positive supply rail and a negative supply rail, each having one end connected to an energy supply device, such as a battery, and one end connected to the equipment. A capacitive filtering element is usually mounted on a secondary line with ends respectively connected to the positive rail and to the negative rail. Since each connection from the circuit to the battery may generate an inrush current that is destructive for the capacitive element, the circuit comprises a module for limiting the inrush current in order to protect the capacitive filtering element. The limiting module controls a switching device placed in the secondary line between the capacitive filtering element and the negative rail, which forms a relatively efficient solution but which has the flaw of introducing an impedance in series with the capacitive filtering element. The circuit furthermore comprises a module for protection against a polarity reversal in order to cut power to the circuit when such a polarity reversal may have consequences detrimental to the correct operation of the equipment. The protection module controls an electromechanical relay disposed on the positive rail upstream of its connection with the secondary line.
The tendency for reduction in weight and size of electrical equipment and of their associated components has a negative impact on the circuits hereinabove and the equipment which they supply such that a need is arising for more compact circuits whose performance and reliability are still at least as good.